The present invention relates to a stacking apparatus for paper sheets having: blade wheel means which is rotated such that an axis of rotation thereof is horizontally aligned and which has elongated wheel blades each extending in a direction opposite to a rotational direction of the blade wheel means from a center portion about the axis of rotation to a peripheral surface of the blade wheel means; feeding means for feeding paper sheets one by one in each of elongated spaces formed between every two adjacent blades of the elongated blades, at a speed exceeding a peripheral velocity of the blade wheel means; and stacking means for stacking the paper sheets sorted by and sequentially discharged in groups of predetermined number, from the blade wheel means.
Paper sheets such as bank notes, data cards, or printed matter are automatically handled. These documents have been increasing year by year. A strong demand has arisen for a machine handling these paper sheets at high speed.
A typical example is a bundling operation for recycling a predetermined number of currency notes. Manual counting and bundling of currency notes is time-consuming and cumbersome. In practice, currency notes are automatically grouped in units of a predetermined number and bundled by a currency note arranger or the like. In the automatic currency note arranger of this type, it is assumed ideal that the currency notes transported at high speed are continuously stacked in units of predetermined numbers without interruption.
Under this condition, there is conventionally provided a stacking means called a beat (direction changing) method in which a paper sheet, discharged from the transporting end and floating in air, is beaten towards a perpendicular direction and dropped onto a stacking unit. However, direction changing means of this type has a limited response speed. More specifically, when a direction changing member vibrates with a given magnitude at high speed, the vibration cycle is increased and with it the inertia force. As a result, operation of the direction changing means becomes unstable. In addition, the force acting on the mechanism of the direction changing means is increased, the means must have a large construction as a whole which results in malfunctions and high cost. In addition to these disadvantages, the force beating the paper sheet is increased, so that the sheet tends to be torn. Therefore, this direction changing means is not suitable for high-speed operation.
A blade wheel is used to overcome the above-mentioned stacking means. The blade wheel has wheel blades, each extending from the center portion to the peripheral surface of the blade wheel. The wheel blades extend in the opposite direction to the rotational direction of the wheel. The paper sheets are inserted in the narrow spaces formed between the blades of the wheel and are stacked. According to this method, the time interval t (min.), during which the leading end of a given paper sheet passes and the leading end of the next paper sheet arrives, is given by observing the paper sheets at a given position along a transporting passage, from: EQU t=1/N
where N is the number of paper sheets fed per minute into the wheel. When the wheel has m narrow spaces between every two adjacent blades, the wheel must be rotated by 1/m revolution during the time interval t. In order to sequentially insert the paper sheets in the corresponding narrow spaces, a rotational speed n (rpm) of the wheel is given as follows: EQU n=(1/m)/(1/N)=N/m
As is apparent from the above equation, the rotational speed n of the wheel is obtained by dividing the number of fed sheets by the number of narrow spaces. The rotational speed of the wheel is very low. Assume that high-speed transportion is performed at the speed of 1800 sheets/min., and that the wheel has 18 narrow spaces. The rotational speed n of the wheel is thus given as 100 rpm (=1800/18). The sheets can be easily stacked at this low speed without any problem.
The blade wheel method has various advantages compared with any other method. Conventionally, a stacking apparatus for paper sheets is provided wherein the blade wheel stacking means is combined with means for sorting paper sheets into units of a predetermined number. According to this stacking apparatus, a separator has an arm having substantially the same axis of rotation as that of the wheel and extending from the center portion around the axis of rotation of the wheel to the outside of the peripheral surface of the wheel, along the side of the wheel. The separator also has a receiving portion integrally formed at the distal end of the arm. The separator is pivoted as needed to abut the arm against the paper sheet inserted between the blades, so the paper sheet is removed from the space formed between the corresponding blades. The paper sheet is temporarily held by the receiving portion. During this period, the sheets, previously discharged from a stationary stopper and stacked on the stacking means, are removed to a predetermined portion. Thereafter, the sheets stacked on the separator are transferred to the stacking means.
However, the following problem is presented by the conventional stacking apparatus having a combination of blade-wheel stacking means and the sorting means. When temporarily receiving paper sheets outside the predetermined number, the arm of the separator is used as a stopper to remove these subsequent paper sheets which are sequentially held by the receiving portion. The arm is located within the width, along the axis of rotation of the wheel, of the paper sheet insertion position in the space of the blade wheel. For this reason, when the separator is located between the sheet feeding position and the sorting start position (receiving start position), the sheet receiving depth of the space of the wheel becomes shallow due to the presence of the arm. Therefore, when the separator is located between the above-mentioned positions, only the leading end of the paper sheet is inserted in a given space, and the trailing end extends outside and blocks the next space. As a result, the next paper sheet cannot be inserted in the corresponding space and collides with the blocking paper sheet, causing a paper jam. In order to prevent this, the transport distance between the adjacent paper sheets approaching the blade wheel must be increased. This prohibits any increase in handling speed.